Funding for this research was provided by:
Narodowe Centrum Nauki (OPUS/UMO-2015/19/B/ST7/02200)
Text and Data Mining valid from 2018-07-05
Received: 24 May 2018
Accepted: 25 June 2018
First Online: 5 July 2018
: The authors declare that they have no competing interests.
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